// Copyright 2016 The LUCI Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package utils

import (
	"encoding/pem"
	"fmt"
)

// ParsePEM takes pem-encoded block and decodes it, checking the header.
func ParsePEM(data, header string) ([]byte, error) {
	block, rest := pem.Decode([]byte(data))
	if len(rest) != 0 || block == nil {
		return nil, fmt.Errorf("not a valid %q PEM", header)
	}
	if block.Type != header {
		return nil, fmt.Errorf("expecting %q, got %q", header, block.Type)
	}
	return block.Bytes, nil
}

// DumpPEM transforms block to pem-encoding.
//
// Reverse of ParsePEM.
func DumpPEM(data []byte, header string) string {
	return string(pem.EncodeToMemory(&pem.Block{
		Type:  header,
		Bytes: data,
	}))
}
